import clsx from "clsx";
import { useTranslation } from "react-i18next";
import { Layers } from "lucide-react";
import { formatNumber } from "../../lib/format";

// At a million and above we stop printing the exact figure — six digits is the readable ceiling, so
// the pill shows "1M+" and the tooltip carries the precise number.
const OVERFLOW_AT = 1_000_000;

// A compact, FIXED-WIDTH count pill for a toolbar: the filtered item count at the toolbar's 28, flat
// and tonal like a `Badge` (the same opaque `bg-tint`: the toolbar is glass over scrolling thumbnails)
// — no edge, because it does nothing (edged = pressable, flat = just
// says; it used to wear the filter dropdowns' glass pill and read as one more). The fixed width is the point — a
// changing number must never shove the controls beside it, so the box is sized to the widest value
// ("999,999 items") and the content is centred within it. A count of a million or more collapses to
// "1M+", with the exact figure in the title tooltip. Deliberately generic ("item(s)", dynamic plural)
// so any surface can reuse it for whatever it counts. `stale`: the count is the previous filter's,
// kept while the new one loads (keepPreviousData) — dimmed, and "updating" for a screen reader (which
// does not voice aria-busy on plain text), so a broad search's slow count ("a": ~3 s) never reads as
// the new result. `failed`: the count could not be read — a dash that says so, not the icon-only box
// of a first load.
export default function ItemCount({
  count,
  stale = false,
  failed = false,
}: {
  count?: number;
  stale?: boolean;
  failed?: boolean;
}) {
  const { t, i18n } = useTranslation();
  const lang = i18n.language;
  // `count` undefined and not `failed`: a first, un-cached load — keep the fixed box (nothing shifts),
  // just show the icon until the number arrives.
  const label = failed
    ? "—"
    : count == null
      ? ""
      : t("common.itemCount", {
          count,
          formattedCount: count >= OVERFLOW_AT ? "1M+" : formatNumber(count, lang),
        });
  return (
    <span
      data-testid="item-count"
      title={
        failed ? t("common.countFailed") : count == null ? undefined : formatNumber(count, lang)
      }
      aria-busy={stale || undefined}
      className="inline-flex h-7 min-w-[9rem] shrink-0 items-center justify-center gap-1.5 rounded-full bg-tint px-3 text-sm whitespace-nowrap text-muted"
    >
      <Layers className="h-3.5 w-3.5 shrink-0 text-muted" aria-hidden="true" />
      <span className={clsx("tabular-nums transition-opacity", stale && "opacity-60")}>
        {label}
      </span>
      {failed && <span className="sr-only">{t("common.countFailed")}</span>}
      {stale && !failed && <span className="sr-only">{t("common.countUpdating")}</span>}
    </span>
  );
}